diff --git a/src/pf1e_simulator/combat.py b/src/pf1e_simulator/combat.py
index ab758df..630edf2 100644
--- a/src/pf1e_simulator/combat.py
+++ b/src/pf1e_simulator/combat.py
@@ -177,6 +177,7 @@ _CHARGE_ATTACK_BONUS = 2  # PF1e: +2 attack roll on a charge
 _CHARGE_AC_PENALTY = 2  # PF1e: -2 AC until start of next turn after charging
 _CHARGE_MIN_CELLS = 2  # PF1e: charge must move at least 10 ft (2 squares)
 _UP_CLOSE_RANGE_FT = 30  # PF1e: Up Close and Deadly works within 30 ft
+_GRAPPLED_CMB_PENALTY = 2  # PF1e: grappled/pinned -2 on non-grapple/escape CMB
 # PF1e: Point-Blank Shot grants +1/+1 within 30 ft with ranged weapons
 _POINT_BLANK_RANGE_FT = 30
 _FIRING_MELEE_PENALTY = -4  # PF1e: ranged attack into melee
@@ -4580,7 +4581,22 @@ class CombatEngine:
         # check is not penalized (a skill check is not a CMB check) — see
         # _maneuver_escape.
         pa_amt = self._power_attack_amt(state)
-        attacker_cmb = self._maneuver_cmb(state) - pa_amt
+        # PF1e (SRD Conditions - Grappled / Pinned): a grappled or pinned
+        # creature takes a -2 penalty on "all attack rolls AND combat
+        # maneuver checks, except for those made to escape or break a
+        # grapple". Escape returned to its own handler above; initiating a
+        # grapple is the exempt check. _maneuver_cmb stays a pure stat
+        # (the concentration DC reads the grappler's CMB, not a check).
+        grapple_penalty = (
+            _GRAPPLED_CMB_PENALTY
+            if maneuver != "grapple"
+            and (
+                self._has_condition_named(state, "grappled")
+                or self._has_condition_named(state, "pinned")
+            )
+            else 0
+        )
+        attacker_cmb = self._maneuver_cmb(state) - pa_amt - grapple_penalty
         target_cmd = self._maneuver_cmd(target)
         roll = self._rng.d20()
         # PF1e (CRB Combat Maneuvers): the provoked-AoO damage rides the
diff --git a/tests/test_maneuvers.py b/tests/test_maneuvers.py
index 412cb52..afeac05 100644
--- a/tests/test_maneuvers.py
+++ b/tests/test_maneuvers.py
@@ -671,3 +671,63 @@ def test_adjacent_grapple_does_not_move_the_target() -> None:
     assert b.pos == (1, 2)
     assert b.grappled_with == "a"
     assert not any("grapple pulls" in line for line in engine._transcript)
+
+
+# --- Grappled / pinned -2 on combat maneuver checks --------------------------
+
+
+def _conditioned(a: CombatantState, name: str) -> None:
+    a.active_conditions.append(
+        ActiveCondition(
+            condition=CONDITIONS_BY_NAME[name], rounds_left=1, source="test"
+        )
+    )
+
+
+def test_grappled_attacker_takes_minus2_on_trip_cmb() -> None:
+    # SRD Conditions - Grappled: "-2 penalty on all attack rolls and combat
+    # maneuver checks, except for those made to escape or break a grapple."
+    # a CMB 2 - 2 = 0 vs b CMD 12: d20 10 -> total 10 < 12 -> FAILED (the
+    # pre-fix engine would have succeeded at 10 + 2 = 12).
+    a = make_state(make_combatant("a", attack_bonus=2), "players", (1, 1))
+    b = make_state(make_combatant("b"), "monsters", (1, 2))
+    _conditioned(a, "grappled")
+    engine = make_engine([1, 10], [a, b])
+    engine._execute_maneuver(a, b, "trip")
+    assert not any(c.condition.name == "prone" for c in b.active_conditions)
+    assert engine._transcript[-1].endswith("-> FAILED")
+
+
+def test_pinned_attacker_takes_minus2_on_trip_cmb() -> None:
+    # Same -2 applies to a pinned creature (SRD Conditions - Pinned).
+    a = make_state(make_combatant("a", attack_bonus=2), "players", (1, 1))
+    b = make_state(make_combatant("b"), "monsters", (1, 2))
+    _conditioned(a, "pinned")
+    engine = make_engine([1, 10], [a, b])
+    engine._execute_maneuver(a, b, "trip")
+    assert not any(c.condition.name == "prone" for c in b.active_conditions)
+    assert engine._transcript[-1].endswith("-> FAILED")
+
+
+def test_grappled_attacker_grapple_check_is_exempt() -> None:
+    # The -2 does NOT apply to grapple checks (escape or break a grapple):
+    # d20 10 + CMB 2 = 12 >= CMD 12 -> SUCCESS.
+    a = make_state(make_combatant("a", attack_bonus=2), "players", (1, 1))
+    b = make_state(make_combatant("b"), "monsters", (1, 2))
+    _conditioned(a, "grappled")
+    engine = make_engine([1, 10], [a, b])
+    engine._execute_maneuver(a, b, "grapple")
+    assert b.grappled_with == "a"
+    assert engine._transcript[-1].endswith("SUCCESS (grappled)")
+
+
+def test_grappled_escape_check_is_exempt() -> None:
+    # Escape is handled by _maneuver_escape which never applies the penalty:
+    # escape bonus = CMB 2 (no -2), d20 10 -> total 12 >= CMD 12 -> freed.
+    a = make_state(make_combatant("a", attack_bonus=2), "players", (1, 1))
+    b = make_state(make_combatant("b"), "monsters", (1, 2))
+    _grappled_by(a, b)
+    engine = make_engine([10], [a, b])
+    engine._maneuver_escape(a, b)
+    assert a.grappled_with is None
+    assert not any(c.condition.name == "grappled" for c in a.active_conditions)